Patient specific and standard sized bone resection cutting guides (“cutting guides”) are well known in joint replacement surgery. Cutting guides help the surgeon prepare the patient's anatomical structures (i.e., bone) for ideal positioning of joint replacement components, such as knee implant components, for optimal joint balancing and prosthesis positioning. Bone resection accuracy is important as the resected bone surfaces can influence the positioning and/or orientation of implant components, which have a resulting effect on implant performance, patient mobility/stability and prosthesis long-term efficacy. Many cutting guides have a variety of cutting guide structures and/or surfaces, such as flat surfaces, slotted cutting surfaces or adjustable slotted surfaces. Typically, a surgeon will make an incision into and through the skin and soft tissues to access a patient's bony structures. In many instances, soft tissue structures will be released or otherwise modified, especially where they obstruct the selected bone surface for resection. In most cases, however, there are at least some surrounding soft tissue structures that are maintained intact to provide stability for the treated extremity and facilitate patient rehabilitation of the treated structures to desirably restore native function and movement in the joint.
Since many surrounding soft tissue structures are desirably unaffected and/or unmodified during a given joint surgery procedure, a surgeon cutting into and/or through bone and/or soft tissue structures must be careful to follow the various cutting guide surfaces with their saw blade or other cutting or drilling tool. Surrounding soft tissue structures will desirably be avoided, as unintentional damage to such areas can cause significant tissue damage and/or significantly degrade the outcomes resulting from the surgical procedure. Moreover, cutting depth control can also be important during a surgical procedure, as the cutting tools can unintentionally exit the intended bone or other cut tissues, with potentially negative consequences for surrounding tissues.
In many cases, it can be difficult to predict whether a given surgical cut will accidentally cut something other than an intended bone or other tissue structure, especially where the entire periphery of the structure being cut cannot be directly and/or indirectly visualized. There can be multiple contributing factors that result in unintentional injury or damage (i.e., cutting) of surrounding tissue structures, such as improper positioning and/or movement of the cutting guide, saw blade deflection, saw blade toggle, movement of the saw blade within the clearance slots of the guide, and/or over-extension (i.e., excessive advancement) of the saw blade, drill or rongeur (or other cutting devices) into surrounding soft and/or hard tissue structures. As previously noted, an accidental injury to surrounding tissues can have significant consequences for the patient, including excessive bleeding, tissue or nerve damage and infection, as well as possibly delaying the patient's recovery and/or creating joint instability that leads to an inability to restore or rehabilitate the patient's native and/or desired joint kinematics.
Traditionally, surgeons have attempted to protect surrounding hard or soft tissue structures by placing rigid retractors or other devices between the edges of the bone (where they anticipate the saw blade might exit the bone) and the protected tissues, desirably to protect these tissue structures from accidental injury from cutting tools. Such retractors are typically designed with various standard arches, curvatures, shapes, sizes and/or widths, and a number of such sizes and shapes are often provided in a kit. But there is no guarantee that these “standard” shapes and sizes will be an appropriate fit for a selected anatomical structure of the joint, creating an uncertainty that a selected retractor will be in an appropriate position to protect adjacent hard or soft tissue structures from an accidental excursion of the saw blade. Moreover, numerous separate attachments, tools or fixtures might be necessary to maintain a given retractor's position during resection of the bone. In addition, where a surgical retractor is manually held in a desired position (i.e., by a handle), the retractor may slide off the bone and/or move unintentionally during the cutting procedure or may not have been positioned in a correct location in the first place, thus increasing the chances of cutting or injuring surrounding hard or soft tissue structures.